When forming images by superposing toner images of a plurality of colors, the toner is transferred to regions (hereinafter called “objects”) that constitute the image. A phenomenon called “toner scatter” is known to occur during this image-forming operation, whereby toner transferred to positions near edges of the objects scatters outside of the objects.
Conventional techniques have been proposed for suppressing toner scatter. For example, one method involves determining in advance the portion of toner extending beyond edges of an image and to reduce the quantity of toner used near the edges of the image based on this calculated portion.